Oxidation inhibitors for photographic materials

ABSTRACT

Photographic developers containing (1) a 3-pyrazolidone, (2) either an ascorbic acid or a mixture of an ascorbic acid with a polyhydroxybenzene compound, and (3) an alkali metal or ammonium salt of a hydroxylated polybasic organic acid as an oxidation inhibitor. Photographic elements containing the developer are also described as well as a chemical transfer process utilizing such photographic elements.

United States Patent Kunz et al.

[451 Apr. 25, 1972 [54] OXIDATION INHIBITORS FOR PHOTOGRAPHIC MATERIALS [72] Inventors: Patrick Kunz; Maurice Edgar Piaff; Pierre Amedee Roman, all of Vincennes, France [21] Appl. No.: 661,210

[30] Foreign Application Priority Data Aug. 30, 1966 France ..74582 [52] US. Cl... ..96/29, 96/66.4 [51] Int. Cl ..G03c 5/54 [58] Field of Search ..96/29, 66.4, 76, 95

[56] References Cited UNITED STATES PATENTS 3,041,170 6/1962 l-Iaist et al ..96/76 3,189,454 6/1965 Luckey et al.. ...96/95 3,201,246 8/1965 Allen et al. ...96/95 3,419,395 12/1968 von K'mig et a1 ..96/95 3,312,550 4/1967 Stewart et a1. ..96/95 2,688,549 9/1954 James et al. .....96/66 3,041,170 6/1962 Haist et al ..96/66 OTHER PUBLICATIONS R. L. Smith, The Sequestration of Metals, Macmillan Co., N.Y. 1959. Pgs. 1, 3, 26, 27,161,162.

A. Martel] & M. Cabien Chemistry of Metal Chelate Compounds, Prentice Hall, 1952 Pgs. l, 9, 10, 134- 139.

L. F. A. Mason, Photographic Processing Chemistry," Focal Press, (1966) Pgs. 51- 56, 59- 62.

Primary Examiner-Norman G. Torchin Assistant Examiner-John L. Goodrow Attorney-W. H. J. Kline, Bernard D. Wiese, Harold E. Cole and Henry E. Byers [57] ABSTRACT Photographic developers containing (1) a 3-pyrazolidone, (2) either an ascorbic acid or a mixture of an ascorbic acid with a polyhydroxybenzenc compound, and (3) an alkali metal or ammonium salt of a hydroxylated polybasic organic acid as an oxidation inhibitor. Photographic elements containing the developer are also described as well as a chemical transfer process utilizing such photographic elements.

22 Claims, No Drawings OXIDATION INHIBITORS FOR PHOTOGRAPHIC MATERIALS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to photographic materials, their preparation and use. In one of its aspects,this invention relates to photographic developer compositions which'have increased stability due to noveloxidation inhibitors. In another of its aspects, this invention relates to photographic elements containing said developer compositions which have increased stability. Another aspect of the invention relates to a chemical transfer process which employs said photographic elements.

2. Description of the Prior Art It is well known that aerial oxidation adversely a'ffectsthe stability of photographic developing agents; When these developing agents are incorporated into a diffusion transfer element, aerial oxidation will cause a loss in development speed which will severely limit the effectiveness of the process. Sultite, usually as sodium sulfite, has been widely used as a developing agent oxidation'inhibitor, but because of its solvent action on silver halides, it creates certain disadvantages in some systems.

U.S. Pat. No. 3,312,550 of Stewart et al. issued Apr. 4, 1967, describes photographic elements containing a 3- pyrazolidone developing agent and either a polyhydroxybenzene compound or ascorbic acid as an auxiliary developing agent. However, if no oxidation inhibitor is present, these elements have a very short storage life. When sulfite is used as an oxidation'inhibitor in the element, its solvent power on silver halides causes development in areas'where it should not occur. In a reversal-transfer process, sulfite also has a tendency to dissolve silver halide in unexposed areas before development has taken place, resulting in fogging of the positive image obtained on the receiving sheet. The present invention provides oxidation inhibitors which do not have these disadvantages of sulfite.

ln U.S. Pat. 3,260,598 of Yutzy et al. issued July 12, 1966, the alkali necessary for development is produced when an alkali metal salt is contacted with a slightly water-soluble metal hydroxide. Certain of the alkali'metal salts therein employed are the same as the alkali metal salts used as oxidation inhibitors in the present invention. However, in the elements described by Yutzy et al., a wide variety of developing agents is employed, while the present invention uses a particular combination of developing agents for a particular purpose. In addition, sulfite is used in the Yutzy et al. patent as an oxidation inhibitor, and the alkali metal salts are present only as alkali-releasing agents used in conjunction with a metal hydroxide. In the present invention, alkaline material for development comes from a compound other than the alkali metal salt.

SUMMARY OF THE INVENTION We have found that an alkali metal salt or an ammonium salt of a hydroxylated polybasic organic acid can be used as an oxidation inhibitor for a combination of developing agents comprising a 3-pyrazolidone compound and an ascorbic acid or a mixture of an ascorbic acid with a polyhydroxybenzene compound, especially in the presence of a saccharide. These developing agents, saccharides and oxidation inhibitors can also be contained in a photographic element and the photographic elements used in a chemical transfer process. The oxidation inhibitors of the invention prevent loss of activity of the developer and speed loss of the elements during storage and avoid fogging and unwanted development caused by prior art oxidation inhibitors.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The developer composition of our invention comprises a 3- pyrazolidone developing agent, from about 0.03 to about 13 grams per millimole of the 3-pyrazolidone developing agent of an ascorbic acid, or a mixture thereof with a polyhydroxybenzene compound, containing at least about 50 percent by weight of 'the ascorbic acid as an auxiliary developing agent, and from about 0.30 to about 60 grams per millimole of the 3- pyrazolidone developing agent of an alkali metal or ammonium salt of a hydroxylated polybasic organic acid as an oxidation inhibitor.

Saccharides can be advantageously employed in* our developer composition, in order to increase the keeping properties. Saccharides, such as sucrose or raffinose, can be present in said composition in a concentration ranging from about 0.15 to about 30 grams per millimole of the 3- pyrazolidone developing agent.

Particularly useful oxidation inhibitors are the alkali metal salts and ammonium salts of hydroxylated polybasic organic acids such as tartaric acid and citric acid. A hydroxylated polybasic organic acid is an organic compound which has more than one COOH group per molecule and at least one hydroxy OH group per molecule.

By alkali metal salts are meant salts derived from potassium, sodium, lithium, and other Group I alkali metals, including mixed salts such as, for example, sodium potassium tartrate and the like. Typical examples of the oxidation inhibitors of v the invention include sodium citrate, potassium citrate, ammonium citrate, sodium tartrate, potassium tartrate, sodium potassium tartrate, ammonium tartrate, etc. Mixtures of these salts can also be employed. In the most preferred embodiments, sodium citrate and sodium tartrate are employed as oxidation inhibitors.

, We employ 3-pyrazolidone developing agents in the invention because they are unique in their activity in chemical transfer processes as compared to other silver halide developing agents. When other developing agents such as monomethyl-p-aminophenol are employed, only a faint silver image is obtained. The auxiliary developing agent serves to control the amount of 3-pyrazolidone developing agent necessary for effective development. An additional advantage of the developing agent combination of the invention is that it yields colorless oxidation products, thus minimizing staining.

Among the 3-pyrazolidone developing agents which are particularly useful in the developer compositions and photographic elements of our invention are those which have the following general formula in which R, can be an alkyl group containing one to 12 carbon atoms, benzothiazolyl or an aryl group of the benzene or naphthalene series, substituted or not R R R and R can be hydrogen, alkyl groups containing one to 12 carbon atoms, or aryl groups such as phenyl and naphthyl, substituted or not; and R can be hydrogen, an alkyl group, an acyl group or an aryl group.

Typical 3-pyrazolidone compounds which can be employed include 1-phenyl-3-pyrazolidone; l-p-tolyl-3-pyrazolidone; lphenyl-4 -methyl-3-pyrazolidone; 1-phenyl-4,4-di'methyl-3- pyrazolidone; and lp-chlorophenyl'3-pyrazolidone. Other useful 3-pyrazolidones are described in U.S. Pat. No. 3,312,550 of Stewart et al. issued Apr. 4, 1967. In a prepared developer solution, a useful concentration of the 3- pyrazolidone compound is from about 1.5Xl0' to 30x10 moles per liter.

These 3-pyrazolidone developing agents are used with an ascorbic acid or a mixture thereof with a polyhydroxybenzene compound as an auxiliary developing agent. Ascorbic acid developing agents which are useful as auxiliary developing agents include dand l-ascorbic acid, d-arabo ascorbic acid, iminoglycoascorbic acid, and other ascorbic acids having the formulas shown in US. Pat. No. 2,688,548 of James et al. is sued Sept. 7, 1954. Polyhydroxybenzene compounds which are useful as auxiliary developing agents in combination with the ascorbic acid include hydroquinone; catechol;

chlorohydroquinone; pyrogallol; bromohydroquinone; isoproylhydroquinone; toluhydroquinone; methylhydroquinone; 2,3-dichlorohydroquinone; 2,S-dimethylhydroquinone; 2,3- dibromohydroquinone; 1,4-dihydroxy-2-acetophenone-2,5- dimethylhydroquinone; 4-phenyl catechol; 4-phenethyl catechol; 4-phenpropyl catechol; 4-t-butyl catechol; 4-n-butylpyrogallol; 4,5-dibromocatechol; 2,5diethylhydroquinone; 2,5-di-p-phenethylhydroquinone; 2,5- dibenzoylaminohydroquinone; 2,5-diphenyl-3,6-dibenzylhydroquinone; 2,5-diacetaminohydroquinone, etc. Esters of such compounds, e.g., formates and acetates, can also be employed.

The developer compositions of the invention are particularly useful when incorporated into a light-sensitive photographic element. In a particular embodiment of the invention, such a photographic element comprises a support coated with a silver halide layer, the element containing from about 12.5 to about 250 grams per mole of silver in the silver halide layer of a 3-pyrazolidone developing agent, from about 7.5 to about 150 grams per mole of silver in the silver halide layer of ascorbic acid, or a mixture thereof with a polyhydroxybenzene compound containing at least about 50 percent by weight of the ascorbic acid, as an auxiliary developing agent, and from about 125 to about 2,500 grams per mole of silver in the silver halide layer of an alkali metal or ammonium salt ofa hydroxylated polybasic organic acid as an oxidation inhibitor. The silver halide layer preferably is a silver halide emulsion.

Saccharides can be employed in the photographic element in order to improve the stability of the emulsion upon aging for extended periods of time. One further effect of the Saccharides, especially of the non-reducing oligosaccharides such as sucrose and raffinose, results from their ability to enhance the development activity of the 3-pyrazolidone developing agents, alone or in combination with the auxiliary developing agents. Thus in the presence of a saccharide, much less of the 3-pyrazolidone compound need be used in the sensitive elements to maintain high development activity. Representative saccharides which can be used are fructose, glucose, inulin, melecitose, pectin, raffinose, starch, sucrose and trehalose. The non-reducing oligosaccharides such as sucrose and raffinose are especially useful. Non-reducing" has a meaning herein usually applied to saccharides and means that the compounds are members of the class of saccharides which do not reduce alkaline solutions of salts of metals such as copper salts, as present in Fehlings solution, as compared to reducing sugars like fructose. The saccharides are advantageously present in the negative element in a concentration ranging from about 30 to 1,000 grams per mole of silver halide.

Any basic substance whatsoever can be used as the alkaline material necessary to activate the developer compositions of the invention. These alkaline materials can be incorporated into a photographic element of the invention or applied from solution. Useful alkaline materials include inorganic alkalis such as sodium metaborate, sodium hydroxide, and sodium carbonate, and organic bases such as, for example, guanidine. When the developer compositions are incorporated into a light-sensitive element, it is advantageous to maintain a relatively low pH, preferably from about 9 to l 1. By using sodium metaborate as the alkaline material, it is possible to obtain such pH values easily. Any concentration of the alkaline material which will effect development can be used. A particularly useful concentration range is from about 0.4 gram to grams per square meter.

The oxidation inhibitors of the invention are also advantageously employed in a chemical transfer process. In the chemical transfer process of the invention, an exposed photographic element comprising a support coated with a silver halide layer, the photographic element containing from about 12.5 to about 250 grams per mole of silver in the silver halide layer of a 3-pyrazolidone developing agent, from about 7.5 to

about 150 grams per mole of silver in the silver halide layer of ascorbic acid, or a mixture of an ascorbic acid with a polyhydroxybenzene compound, containing at least about 50 percent by weight of the ascorbic acid, as an auxiliary developing agent, and from about to about 2,500 grams per mole of silver in the silver halide layer of an alkali metal or ammonium salt of a hydroxylated polybasic organic acid as an oxidation inhibitor, is contacted in the presence of water and of an alkaline compound with a receiving element containing a silver halide solvent and a silver-precipitating agent. Preferably the photographic element also contains a saccharide, as mentioned above. According to an advantageous embodiment, the alkaline material is incorporated to the said photographic element which is treated with water before contacting it with the receiving element.

The receiving element in this chemical transfer process can also contain a neutralizing agent. Such a neutralizing agent is a compound which will neutralize the acidity of the paper used in the receiving element and thus give improved chemical transfer images. Preferred compounds which are used as neutralizing agents include sodium fluoride, sodium oxalate, sodium metaborate, the tetrasodium salt of ethylenediaminetetraacetic acid, and the like, and mixtures thereof. The neutralizing agent can be present in the receiving element in any concentration which will effect the desired neutralization.

Chemical transfer processes, which are well known, utilize the undeveloped silver halide in non-image areas of the negative to form a positive by dissolving the undeveloped silver halide and precipitating it on a silver layer in close proximity to the original silver halide emulsion layer. Such processes are described in U.S. Pat. Nos. 2,352,014 of Rott issued June 20, 1944; 2,543,181 of Land issued Feb. 27, 1951; and 3,020,155 of Yackel et al. issued Feb. 6, 1962.

Silver-precipitating agents that can be incorporated in the receiving elements of the invention can be physical development nuclei or chemical precipitants including (a) heavy metals, especially in colloidal form, and the salts of these metals, (b) salts, the anions of which form a silver salt less soluble than the silver halide of the photographic emulsion to be processed, or (c) nondiffusing polymeric materials with functional groups capable of combining with and insolubilizing silver ion. Examples of such silver-precipitating agents includes sulfides, selenides, polysulfides, polyselenides, thiourea and its derivatives, mercaptans, stannous halides, silver, gold, platinum, palladium, and mercury, colloidal sulfur, aminoguanidine sulfate, aminoguanidine carbonate, arsenous oxide, sodium stannite, substituted hydrazines, xanthates, and the like. Heavy metal sulfides such as lead, silver, zinc, nickel, antimony, cadmium, and bismuth sulfides are useful, particularly the sulfides of lead and zinc, alone or in admixture, or complex salts of these with thioacetamide, dithio-oxamide, or dithiobiuret. Suitable silver precipitating agents for use in the receiving elements of the invention are disclosed in U.S. Pat. No. 2,352,014 of Rott issued June 20, 1944; U.S. Pat. No. 2,740,717 of Yutzy et al. issued Apr. 3, 1956; and U.S. Pat. No. 3,020,155 of Yackel et al. issued Feb. 6, 1962. The concentration of the silver-precipitating agent in the receiving element must be sufficient to insure positive and complete removal of undeveloped silver halide from the light-sensitive element. However, a very considerable degree of control of the sensitometric properties of the image produced can be obtained by the choice of the silver precipitant and its concentration. A useful concentration range for the silver-precipitating agent is from about 0.01 milligram to about 0.1 gram per square meter.

Any customary silver halide solvent can be used in the receiving elements of the invention, including alkali metal thiosulfates such as sodium thiosulfate, potassium thiosulfate, etc., alkali thiocyanates, alkali selenocyanates, thioglycerol, aminoethanethiols, p,p'-dithiosuberic acid, etc. The silver halide solvent can be used in any concentration which will achieve the desired result, and a particularly useful concentration range is from about 0.5 gram to 3 grams per square meter.

The various processing constituents necessary for develop ment of the photographic elements of the invention developing agents, oxidation inhibitor, alkaline material, silver halide solvent, saccharide, etc., can be incorporated in the same or different layers of an element or in the same or different elements. They can be incorporated directly into the silver halide emulsion layer (except for the silver halide solvent) or in a layer contiguous to the emulsion layer. Some of the processing constituents can be incorporated into the light-sensitive element while others are in the receiving element. The developing agents can be incorporated into the light-sensitive element with processing effected by contacting the element with an alkaline activator solution. If all the necessary processing constituents are incorporated into the elements, contacting the sensitive element with a receiving or processing element in the presence of water alone will cause development. If sufficient moisture is present in the elements, merely applying heat to the contacted elements will also cause development.

The silver halide emulsion of a photographic element useful in this invention can contain conventional addenda such as gelatin plasticizers, coating aids, antifoggants such as the azaindines and hardeners such as aldehyde hardeners, e.g., formaldehyde, mucochloric acid, glutaraldehyde bis(sodium bisulfite), maleic dialdehyde, aziridines, dioxane derivatives and oxypolysaccharides. Sensitizing dyes useful in sensitizing such emulsions are described, for example, in U.S. Pat. Nos. 2,526,632 of Brooker and White issued Oct. 24, 1950, and 2,503,776 of Sprague issued Apr. 11, 1950. Spectral sensitizers which can be used are the cyanines, merocyanines, complex (trinuclear) cyanines, complex (trinuclear) merocyanines, styryls, and hemicyanines. Various silver salts can be used as the sensitive salt such as silver bromide, silver iodide, silver chloride, or mixed silver halides such as silver chlorobromide or silver bromoiodide. The silver halides used can be those which form latent images predominantly on the surface of the sliver halide grains or those which form latent images inside the silver halide crystals such as described in U.S. Pat. No. 2,592,250 of Davey and Knott issued Apr. 8, 1952.

The silver halide emulsion layer of a photographic element which is useful in the instant invention can contain any of the hydrophilic, water-permeable binding materials suitable for this purpose. Suitable materials include gelatin, colloidal albumin, polyvinyl compounds, cellulose derivatives, acrylamide polymers, etc. Mixtures of these binding agents can also be used. The binding agents for the emulsion layer of the photographic element can also contain dispersed polymerized vinyl compounds. Such compounds are disclosed, forexample, in US. Pat. Nos. 3,142,568 of Nottorf issued July 28, 1964; 3,193,386 of White issued July 6, 1965; 3,062,674 of Houck et al. issued Nov. 6, 1962; and 3,220,844 of Houck et al. issued Nov. 30, 1965; and include the water-insoluble polymers of alkyl acrylates and methacrylates, acrylic acid, sulfoalkyl acrylates or methacrylates and the like.

The silver halide emulsion of a photographic element which is useful in the instant invention can be coated on a wide variety of supports. Typical supports are cellulose nitrate film, cellulose ester film, polyvinyl acetal film, polystyrene film, poly(ethylene terephthalate) film and related films or resinous materials as well as glass, paper, metal and the like. Supports such as paper which are coated with a-olefin polymers, particularly polymers of a-olefins containing two or more carbon atoms, as exemplified by polyethylene polypropylene, ethylene-butene copolymers and the like can also be employed.

The sensitometric characteristics of the photographic emulsions useful in the instant invention can be further enhanced by including in the emulsions a variety of hydrophilic colloids such as carboxymethyl protein of the type described in US. Pat. No. 3,011,890 of Gates, .lr., et a1. issued Dec. 5, 1961, and polysaccharides of the type described in Canadian Pat. No. 635,206 of Koller et a1. issued Jan. 23, 1962.

Photographic emulsio'ns useful in the instant invention can also contain speed-increasing compounds such as quaternary ammonium compounds, polyethylene glycols or thioethers. Frequently, useful effects can be obtained by adding the aforementioned speed-increasing compounds to the photographic developer solutions instead of, or in addition to, the photographic emulsions.

The photographic elements prepared according to the instant invention can be used in various kinds of photographic systems. In addition to be useful in X-ray and other non-optically sensitized systems, they can also be used in orthochromatic, panchromatic and infrared sensitive systems. The sensitizing addenda can be added to photographic systems before or after any sensitizing dyes which are used.

Silver halide emulsions useful in the instant invention can be sensitized using any of the well-known techniques in emulsion making, for example, by digesting with naturally active gelatin or various sulfur, selenium, tellurium compounds and/or gold compounds. The emulsions can also be sensitized with salts of noble metals of Group VIII of the Periodic Table which have an atomic weight greater than 100.

The following examples will illustrate the invention but are not to be construed to limit it in any way.

EXAMPLE 1 Developers of the following composition are prepared:

Developer A (Control) Sodium metaborate-4H 0 25 grams Sucrose 25 grams Ascorbic acid 4 grams l-Phenyl-3-pyrazolidone 1 gram Water to make 1,000 milliliters Developer B Developer A Sodium tartrate At After After Start 24 Hours 48 Hours Developer A 1.30 0.90 0.30 Developer B 1.30 1.30 1.10

Thus, the addition of sodium tartrate as an oxidation inhibitor considerably reduces the loss in activity of the developer with the passage of time.

EXAMPLE 2 The following developer composition is prepared:

Bone gelatin grams Sodium metaborate'4l-l O 100 grams Sucrose 100 grams Sodium tartrate 200 grams Ascorbic acid 9 grams 1-Phenyl-3-pyrazolidone 10 grams Methanol 200 grams Formaldehyde 10% solution) 4 milliliters Saponin 15% solution) 30 milliliters Water to make 2.5 liters um citrate is substituted for sodium tartrate in the developer layer.

The coated papers which contain sodium citrate or sodium tartrate show no deterioration after 6 months storage under controlled conditions at a relative humidity of 35 percent, or after drying for 7 days at 50 C. Similar negatives which contained no sodium citrate or sodium tartrate can no longer be developed after 1 months storage or after drying for 7 days at 50 C.

EXAMPLE 3 A composition of nuclei is prepared from the following solutions A Bone gelatin 1 13 grams Water 3,500 cc B Na s normal solution 7.5 cc

C NiCl normal solution 7.8 cc

Water 600 cc Solution B is poured into Solution A at 40 C, then Solution C into the resulting mixture, in 4 minutes. The weight is adjusted to 4,860 grams.

A conventional NiS-nucleated receiving element is made from a solution having the following composition:

Bone gelatin 20 grams NiS nuclei Composition (prepared above 100 grams Sodium thiosulfate grams Sodium metaborate-4H,O 60 grams Sodium sulfite grams Mercapto-oxazoline (1% solution) 15 milliliters Saponin (15% solution) 10 milliliters Formaldehyde (10% solution) 10 milliliters Water to make 1,250 milliliters This solution is coated at a coverage of 60 milliliters per square meter onto a document-type paper as a support.

A negative element of Example 2 is given a reflex exposure, immersed in water for a few minutes, and contacted with the receiving element. Good positive copies are obtained.

These operations can be performed in a commercial reversal-transfer machine containing only water as an activator. Water temperature can range between approximately 5 and 50 C.

Although the invention has been described in considerable detail with particular reference to certain preferred embodiments thereof, variations and modifications can be effected within the spirit and scope of the invention as described herein-before and as defined in the appended claims.

We claim:

1. A developer composition comprising a. a 3-pyrazolidone developing agent,

b. from about 0.03 to about 13 grams per millimole of said 3-pyrazolidone developing agent of an auxiliary developing agent selected from the group consisting of an ascorbic acid and a mixture of said ascorbic acid with a polyhydroxybenzene compound containing at least about 50 percent by weight of the ascorbic acid, and

c. from about 0.30 to about 60 grams per millimole of said 3-pyrazolidone developing agent of an alkali metal salt selected from the group consisting of alkali metal salts of citric acid, alkali metal salts of tartaric acid, ammonium citrate, ammonium tartrate, and mixtures thereof.

2. The developer composition of claim 1 wherein said salt is sodium citrate.

3. The developer composition of claim 1 wherein said salt is sodium tartrate.

' 4. The developer composition of claim 1 which also con with a silver halide la er, said element containing:

a. from about 12. to about 250 grams per mole of silver in said silver halide layer of a 3-pyrazolidone developing agent,

b. from about 7.5 to about 150 grams per mole of silver in said silver halide layer of an auxiliary developing agent selected from the group consisting of an ascorbic acid and a mixture of said ascorbic acid with a polyhydroxybenzene compound, containing at least 50 percent by weight of the ascorbic acid, and

. from about to about 2500 grams per mole of silver in said silver halide layer of an alkali metal salt selected from the group consisting of alkali metal salts of citric acid, alkali metal salts of tartaric acid, ammonium citrate, ammonium tartrate, and mixtures thereof.

7. The photographic element of claim 6 wherein said silver halide layer is a silver halide emulsion layer.

8. The photographic element of claim 7 wherein said salt is sodium citrate.

9. The photographic element of claim 7 wherein said salt is sodium tartrate.

10. The photographic element of claim 7 which also contains an alkaline material.

11. The photographic element of claim 7 which also contains an alkaline material.

12. The photographic element of claim 7 which also contains a saccharide.

13. The photographic element of claim 7 which also contains a saccharide.

14. The photographic element of claim 12 wherein said saccharide is sucrose or raffinose.

15. A process for the production of chemical transfer images from an exposed photographic element comprising a support coated with a silver halide layer, said photographic element containing from about 12.5 to about 250 grams per mole of silver in said silver halide layer of a 3-pyrazolidone developing agent, from about 7.5 to about grams per mole of silver in said silver halide layer of an auxiliary developing agent selected from the group consisting of an ascorbic acid and a mixture of said ascorbic acid with a polyhydroxybenzene compound, containing at least about 50 percent by weight of the ascorbic acid, and from about 125 to about 2,500 grams per mole of silver in said silver halide layer of an alkali metal salt selected from the group consisting of alkali metal salts of citric acid, alkali metal salts of tartaric acid, ammonium citrate, ammonium tartrate, and mixtures thereof.

16. The process of claim 15 wherein said salt is sodium citrate.

17. The process of claim 15 wherein said salt is sodium tartrate.

18. The process of claim 15 wherein said receiving element also contains a neutralizing agent.

19. The process of claim 18 wherein said neutralizing agent is selected from the group consisting of sodium fluoride, sodium oxalate, sodium metaborate, the tetrasodium salt of ethylencdiaminetetraacetic acid, and mixtures thereof.

20. The process of claim 15 wherein said alkaline material is incorporated in said photographic element.

21. The process of claim 15 wherein said photographic-element also contains a saccharide.

22. The process of claim 20 wherein said photographic element is treated with water before contacting it with the receiving element. 

2. The developer composition of claim 1 wherein said salt is sodium citrate.
 3. The developer composition of claim 1 wherein said salt is sodium tartrate.
 4. The developer composition of claim 1 which also contains a saccharide.
 5. The developer composition of claim 2 which also contains a saccharide.
 6. A photographic element comprising a support coated with a silver halide layer, said element containing: a. from about 12.5 to about 250 grams per mole of silver in said silver halide layer of a 3-pyrazolidone developing agent, b. from about 7.5 to about 150 grams per mole of silver in said silver halide layer of an auxiliary developing agent selected from the group consisting of an ascorbic acid and a mixture of said ascorbic acid with a polyhydroxybenzene compound, containing at least 50 percent by weight of the ascorbic acid, and c. from about 125 to about 2500 grams per mole of silver in said silver halide layer of an alkali metal salt selected from the group consisting of alkali metal salts of citric acid, alkali metal salts of tartaric acid, ammonium citrate, ammonium tartrate, and mixtures thereof.
 7. The photographic element of claim 6 wherein said silver halide layer is a silver halide emulsion layer.
 8. The photographic element of claim 7 wherein said salt is sodium citrate.
 9. The photographic element of claim 7 wherein said salt is sodium tartrate.
 10. The photographic element of claim 7 which also contains an alkaline material.
 11. The photographic element of claim 7 which also contains an alkaline material.
 12. The photographic element of claim 7 which also contains a saccharide.
 13. The photographic element of claim 7 which also contains a saccharide.
 14. The photographic element of claim 12 wherein said saccharide is sucrose or raffinose.
 15. A process for the production of chemical transfer images from an exposed photographic element comprising a support coated with a silver halide layer, said photographic element containing from about 12.5 to about 250 grams per mole of silver in said silver halide layer of a 3-pyrazolidone developing agent, from about 7.5 to about 150 grams per mole of silver in said silver halide layer of an auxiliary developing ageNt selected from the group consisting of an ascorbic acid and a mixture of said ascorbic acid with a polyhydroxybenzene compound, containing at least about 50 percent by weight of the ascorbic acid, and from about 125 to about 2,500 grams per mole of silver in said silver halide layer of an alkali metal salt selected from the group consisting of alkali metal salts of citric acid, alkali metal salts of tartaric acid, ammonium citrate, ammonium tartrate, and mixtures thereof.
 16. The process of claim 15 wherein said salt is sodium citrate.
 17. The process of claim 15 wherein said salt is sodium tartrate.
 18. The process of claim 15 wherein said receiving element also contains a neutralizing agent.
 19. The process of claim 18 wherein said neutralizing agent is selected from the group consisting of sodium fluoride, sodium oxalate, sodium metaborate, the tetrasodium salt of ethylenediaminetetraacetic acid, and mixtures thereof.
 20. The process of claim 15 wherein said alkaline material is incorporated in said photographic element.
 21. The process of claim 15 wherein said photographic element also contains a saccharide.
 22. The process of claim 20 wherein said photographic element is treated with water before contacting it with the receiving element. 